STANDARD TECHNICAL SPECIFICATIONS FOR ELECTRIC WORKS

OVERHEAD TRANSMISSION LINES

( SPECIFICATION )

SURVEYING WORKS

TRANSCO STANDARD : S-TR-OHL-SURV (REV.0-2018)

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CONTENTS

1 GENERAL ....................................................................................................................... 3
1.1 Drawings ........................................................................................................................... 3
1.2 Equipment Identification and Color Codes ....................................................................... 3
2 TECHNICAL DESCRIPTION ...................................................................................... 3
2.1 General .............................................................................................................................. 3
2.2 Line Routing...................................................................................................................... 3
2.3 Line Profile Survey ........................................................................................................... 4
2.4 Tower Site Survey ............................................................................................................. 5
2.5 Clearing of Right-of-Way ................................................................................................. 6

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SURVEYING WORKS

1 GENERAL
This part of the specification covers overhead line routing, line profile survey, tower site survey,
clearing of right-of-way and access.
For applicable technical standards, tests and general requirements please refer to:
S-TR-OHL-GEN - General Requirements (Applicable Technical Standards, Tests,
etc.)

1.1 Drawings
Typical Drawing for Conceptual Clearances of OHL provided in the Drawings Section is as
follows:
Drawing No. Title
DWG TR OHL 01 01 Conceptual Clearance of OHL

1.2 Equipment Identification and Color Codes

Concerning Surveying Works Identification reference shall be made to Standard Technical
Specification, Part:
S-TR-GEN-ID - Components Marking

2 TECHNICAL DESCRIPTION

2.1 General
The Bidder/Contractor shall keep damage within the right-of-way to a minimum, consistent with
the successful execution of the erection work. The Bidder/Contractor shall exercise all
precautions to avoid damage to crops and other property. The Bidder/Contractor shall comply
with all national and local regulations regarding barricades, detour arrangements, and warning
signs. Damage to roads, footpaths, bridges, ditches, etc., caused by the Bidder/Contractor shall
be repaired at his expense.

2.2 Line Routing

The Bidder/Contractor shall carry out the line routing, in close co-operation with TRANSCO, by
instrument survey, based on the route drawing(s). Owing to the large scale factor of these
drawings, they are of rather general nature and need to be superseded by more detailed maps, to
be prepared by the Bidder/Contractor, in an approved scale. They shall contain comprehensive
information on the route area, noting true coordinates of angle points, and all relevant particulars
on crossed/approximated trees, structures, over- and underground services, etc. Coordinates shall

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be determined precisely by differential GPS and submitted in formats as required by the different
government agencies. For Town Planning Dept., coordinates shall be prepared in UTM system
(datum Narwahn UAE), for the General Civil Aviation Authority WGS-84 geographical
coordinates are to be submitted. Other formats may be required additionally. The detailed route
maps shall be prepared by the Bidder/Contractor in the required quantity and are to be submitted
for TRANSCO s approval, who will forward them to the department of Town Planning and other
relevant authorities, for their approval.
Approval of the maps by the Town Planning Department and other relevant authorities is a pre-
requisite to perform profile survey and tower spotting.
In mountainous areas, aerial survey using LIDAR technology shall be acceptable in order to
improve the quality and the accuracy of the survey, and expedite the line design process.
The Bidder/Contractor shall be prepared to amend the route, according to detailed requirements
of the authorities, until final approval is obtained. No additional costs will be considered for such
minor work. Amendments required after receipt of route approval by the authorities shall be
remunerated as per the relevant contractual rate for survey works.
Before the construction stage, route maps shall be amended for display of line access provisions
(refer to Technical Standard Specification, Part: S-CIVIL-OHL-Item 2.4).

2.3 Line Profile Survey

The topographical line survey shall be carried out along the approved line route.
The theodolites used and measuring techniques applied shall be state of the art, employing digital
recording technique, to TRANSCO s satisfaction. The survey shall be carried out to a minimum
accuracy of 1 in 2.000 for distance- and 1 minute for angular measurements.
The Bidder/Contractor shall prepare longitudinal profile drawings of the transmission line, in
scales of:
1 : 2000 for the horizontal and
1 : 200 for the vertical axis.
The profile plans shall contain the longitudinal ground profile along the OHL centreline, plus
side profiles right and left under the outermost conductors, shown in different broken lines. They
shall display the bottom conductor catenary (at spans adjacent to angle towers for the longest
conductor), at 80°C, together with the ground- or special clearance curves, as well as the
minimum temperature catenary. Tower nos., tower types, weight spans, wind spans, equivalent
spans, section length, continuos chainage, elevations, level differences, UTM coordinates, etc.
shall be shown. Along the bottom of the profile plan, a strip plan of the line route, extending 20
m for HV and 10 m for MV lines beyond the corridor limits, to either side of the centreline, shall
be shown. The strip plan shall detail all relevant information regarding obstructions, services,
vegetation, terrain type, land use, etc.. Horizontal and vertical coordinates of all features
affecting the line construction shall be indicated on the profile plan. Crossings of existing
overhead lines shall be documented with measured elevations and locations of their top and
bottom conductors, at centerline and side profile limits, together with the air temperature at the

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time of measurement. All qualified crossings and approximations shall be covered by individual
clearance calculations, to be shown on the profile plan. Tower centre coordinates and all
elevations shall be reduced to UTM (Universal Transverse Mercator) Narwhan UAE datum, and
indicated on the profile plans.
The Bidder/Contractor shall locate and indicate bench marks and reference points already
existing in the project area for differential GPS positions. TRANSCO will render assistance to
the Bidder/Contractor in providing information about locations of the reference points. Where
these do not exist, the Bidder/Contractor shall provide such reference points in consultation with
e.g. the Town Planning Department, Public Works Department, etc.
The line route shall be marked in the field by timber survey pegs of sufficient length, with a
cross section of min. 50x50 mm, to be driven flush into the ground. The accurate centreline shall

shall be secured by a concrete foundation, to TRANSCO

driven along the OHL centerline, at a minimum of 4 per km, and to either side of every line
crossing. After approval of the tower distribution on the profile plans, tower centre pegs shall be
driven at site. After final approval of tower locations, which will be given by TRANSCO, after
detailed site inspection, insurance pegs shall be driven approx. 50 m to either side of each tower
centre peg, in line direction. Different kinds of pegs shall be distinguishable by a paint marking
system, to be submitted for TRANSCO oval.
All pegs or other marks shall be preserved until their removal is authorized by TRANSCO.
For the purpose of profile/tower location inspection by TRANSCO, all terminal-, angle-, and
other relevant line points shall be marked by red flags with a minimum size of 1.5 x 1.5 m, to be
mounted on min. 5 m high steel bases for HV lines and 1 x 1 m on 2 m high bases for MV lines.
The Bidder/Contractor shall minimize the number of tower locations between line angle points,
without exceeding the tower/conductor design limits. The tower distribution shall be performed
by means of a recognized computerized optimization program, to TRANSCO s approval.
To facilitate approval of profile plans, the Bidder/Contractor shall provide TRANSCO with two
licensed copies of a/m program inclusive of all relevant survey- and other data in digital form,
and with three complete sets of transparent sag templates in perspex or similar material, 4 to 5
mm thick, based on the range of equivalent spans required, staggered at 50 m for HV lines and
20 m for MV lines, and for the conductor types and scales to be used. The templates shall be cut
precisely along the conductor catenary in still air, at maximum temperature (hot curve at 80°C).
The sag curve in still air, at minimum temperature (cold curve at 5°C), the span grid, the ground
clearance line, and all relevant details like design loading conditions, particulars of conductors,
equivalent span applicable, scales, etc. shall be engraved.

2.4 Tower Site Survey

After approval of profile plans with tower distribution for steel lattice towers, the
Bidder/Contractor shall prepare diagonal cross sections of all tower locations, to determine
leg/hillside extensions/reductions, foundation platform/protection requirements, and foundation

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setting levels. It shall be ensured that the foundation concrete caps will have a minimum height
of 0,75 m above final ground level.
Relocation of a tower exceeding the longitudinal deviation limit will be allowed only if approved
by TRANSCO and for purposes of improving soil conditions for foundation work. Such
relocation shall in any case not exceed more than 10 m in either direction and will be allowed,
provided ground clearance is not impaired and specific loading of the particular tower is not
exceeded.
Towers in tangent positions shall be oriented with the transverse faces at right angles to the
transmission line centre line, and towers in angle positions shall be oriented with the transverse
face at right angles to the bisector of the deviation angle. Towers with asymmetrical crossarms
shall be offset from the theoretical centreline, so far as to even out the distance between
conductors of either tower side to the theoretical centreline.
As soon as the final tower locations are agreed and approved by TRANSCO, the
Bidder/Contractor shall submit a line schedule. The line schedule shall indicate route
designation, voltage, conductor type, number and size, tower numbers, tower types, body and leg
extensions, angles of deviation, insulator types, insulator string types, spans, equivalent spans,

can be entered. After the completion of various parts of the works further data, for instance the
foundation types for each tower, locations of mid span joints and repair sleeves, details of
counterpoise or special earthing requirements, and any other information deemed necessary by
TRANSCO shall be added to the line schedule.

2.5 Clearing of Right-of-Way

med, under any circumstances. Reference is made to
circular No. 48, 1991, WED/101/2803. Cutting of other trees shall be avoided, as far as possible.
It shall be clearly understood that the relevant authorities will prosecute any unauthorised cutting
of any plant. Prior to cutting any plant, a written permission from TRANSCO or from the
relevant Authority or Department must be obtained by the Bidder/Contractor.
The Bidder/Contractor shall make the necessary arrangements with property owners, so as to
permit cutting or trimming of trees located both, inside and outside the right-of-way, where such
cutting or trimming is unavoidable. TRANSCO may extend assistance to the extent possible.
In addition, where trees outside the cleared area have such a height that they could fall within 2
meters of the conductors, they shall be cut or trimmed to such a height to avoid such a
possibility.
If trees are found at tower locations, the Bidder/Contractor shall apply for removal by the
relevant Authorities or TRANSCO, for replanting at another place, by the Bidder/Contractor.
Any cost arising from any handling of vegetation is deemed to be included in the Contract price,
it will not be remunerated separately.

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